OCR Text |
Show lGG DOMES'I'IC PIGEONS. CHAP. Y. not all tumblers) non.rly as prominent as that of tho third dorsal vertebra; and tho two hypapophysos together tend to form an ossified arch. Tho d.ovo lopmont of tho arch, formed l>y the hypapophyflos of tho third and fomth dor ·al vortobrro, also varies considerably, as docs tho size of tho hypapophyRis of tho fifth vertebra. Tho ro ·k-pigeon has twolvo sacral vertebrre; but those vary in number, mlativo size, an<l distinctness in tho different broodR. In pouters, with their elon gated bodies, thoro arc thirteen or oven fourteen, and, aR we shall immod.iatoly soc, an additional number of caudal vortobrro. In runts and carriers thoro is genonilly tho proper number, nnmoly twelve; but in one nmt, and in tho 13ussorah canior, thoro wore only cloven. In tumblers thoro aro oithor eleven, twelve, or thirteen sacml vortcbrro. Tho cnudal vertefm.c arc seven in number in tho rock-pigeon. In fantails, which havo thou· tails RO largely dovoloped, there aro citl1Cr eight or nine, and apparently in ono cnso ton, and they aro a littlo longer than in tho rock-pigeon, and thou· . hapo varies considerably. Pouters, also, have eight ot· nino caudal vortcbrro. I have soon eight in a mm andjacobin. Tumblers, though such small birds, n.lways have the normal num bor seven ; as have carl'iors, with one exception, in which thoro woro only six. Tho following tal>lo will servo as a summary, and will show tho most romarkablo deviations in tho number of tho vertobrro and ribs which I have observed:- Cervical Vortebrro Dor~al V crtcbrro Ribs .. 'acral Vertchrro .. Cfl.utbl V l'tcbrro .. '£otal Vcrtobrro .. I~ Rock Pigeon. 12 12 12 Dussomh Carrier. 12 Tho 1 2tb IJorc a small rib. 8 8 8 8 8 8 7 7 Tho 6th pair with The 6th and 7th Til 6th and 7th The 6th und Hh proccsscB, the 7th pair with puir· without pair without pul~;~~~~~~rt a proc sse~. proccllSC6. processes. 12 7 39 14 8 or 9 42 or 43 11 7 11 7 1-s;-~-3-8- . . Tho ?Jel'Vis difl:~rs vor~ little in any brood. Tho anterior margin of tho ~lmm, howcv?r, IS sometnnofl a little more equally rounded on both sides than :~ tho rock-p1gcon, ~ho ischi~m is also frequently rather more elongated. [ ho ~btmator-not?h IS somot1mcs, as in many tumblers, loss developed than m tho rock-p1goon. Tho ridges on the ilium arc very prominent u1 moRt runts. ~ the bon~s of the extremities I could detect no difference except in tl:~~r .proportJo~al lengths.; for instance, tho metatarsus in a ~outer was 1 Gu melt~ ~nd m a short-faced tumbler only ·95 in length· and this is a gre~tcr difforcnco than would natmally follow from their arlrorontly-sizod bo~es; but long logs in the pouter, and small feet in tho tumbler, arc selected pomts. In some pouten; the SC((Jntln is rather sb:aightcr, and in some CIIAP. v. OSTEOLOGICAL DIFFERENCES. 167 tumblers it is straighter, with the apex less elongated, than in the rockpigeon: in tho woodcut, fig. 28, tho scapulro of the rock-pigeon (A), and of a short-faced tumbler (B), are given. 'l'he processes at the summit of the coracoid, which receive the extremities of the furcula, form a more perfect cavity in some tumblers thun in the rock-pigeon : in pouters these processes arc larger and differently shaped, and the exterior anglo of the extremity of the coracoid, which is articulated to the sternum, is squarer. Tho two arms of the fur·c~ tla in pouters diverge less, proportionally to theu· A l:l length, than in tho rock- B Fig. 28.-Scapulro, of nnturat pigeon; and the symphysis size. A. Hock-pigeon. is more solid and pointed n. Short-faced Tumbler. In fantails tho degree of di~ vorgonco of tho two arms varies in a remarkable manner. In fig. 29, B and o represent the furculm of two fantails; and it will bo soon that the divergence in B is rather less even than in the furcula of tho short-faced, small-sized tumbler (A); whereas tho divergence in o equals that in a rookpigeon, or in the pouter (n), though the latter is a much larger bu·d. The extremities of the fUl'cula, whore articulated to the coracoids, vary considerably in outline. In tho sternum the differences in form arc slight, except in the size and outline of tho perforations, which, both in tho larger and lesser sized breeds, arc sometimes small. These perforations, also, aro sometimes either nearly circular, or elongated, as is often tho case with carriers. Tho posterior perforations occasionally aro not complete, being loft open posteriorly. Tho marginal apophyses forming the anterior perforations vary greatly in development. Tho degree ~ of convexity of tho posterior part of tho sternum ~· , differs much, being sometimes almost perfectly flat. Tho manubrium is rather more prominent in some Fig. 29.-Furculro, of natural individuals than in others, and tho pore immediately ~~~~: ~ ~~~t~n~~~~~:S: under it varies greatly in size. D. Pouter. Correlation of Growth.-By this term I mean that the whole organisation is so connected, that when one part varies, other |